Paper feeding devices for transferring individual sheets of paper into an image forming device such as a copier or a printer from a tray of the paper feeder are known. Typically, a stack of paper is positioned on the tray to be individually transferred into the image forming device for imaging by the image forming device. Typically, the paper feeder has a shuttle vacuum feed-head located adjacent to a top side of the stack of paper to separate an uppermost piece of paper from the stack of paper. Additionally, the paper feeder has fluffer jets located adjacent to one or more exterior edges of the stack of paper for separating the sheets of paper within the stack on the tray of the paper feeder prior to feeding the paper into the image forming device.
U.S. Patent Publication No. US 2005/0110207 A1, incorporated herein by reference in its entirety, describes a sheet curl correction method and a feeder apparatus for an electrophotographic printing machine and a vacuum corrugation shuttle feed head. The method for correcting sheet curl in a paper feeder having a tiltable tray comprises (a) detecting a first distance above a surface of a stack of sheets on the tiltable tray to be fed into the printing machine at a first location above the stack of sheets; (b) detecting a second distance above the surface of the stack of sheets on the tiltable tray to be fed into the printing machine at a second location above the stack; and (c) detecting a third distance above the surface of the stack of sheets to be fed into the printing machine at a third location above the stack. The method tilts the tiltable tray based upon the first, second, and third distances detected.
During operation of the image forming device, such as processing tasks, a first valve connected to the shuttle vacuum feed-head opens and reduces air pressure within the feeder adjacent to the uppermost piece of paper and the top side of the stack of paper. A second valve connected to the flutter jets opens to transfer air into the paper feeder adjacent to the exterior edges of the stack of paper. The air pushes or moves between the sheets of paper within the stack to separate one or more sheets of paper. As a result, upper sheets of paper from the stack are separated from each other and are pulled inwardly with respect to the shuttle vacuum feed-head. The shuttle vacuum feed-head may receive a top piece of paper from the stack and may feed the top piece of paper into the image forming device via a take away roll (hereinafter “TAR”) connected to the paper feeder. As a result, the top sheet of paper from the stack is fed into the image forming device, by the TAR, separately with respect to other sheets of paper because the fluffer jets separated or fluffed the stack of paper.
Often, sheets of paper have exterior surfaces with a coating, such as for gloss, which may permit moisture to collect between the sheets of paper within the stack. Such moisture may cause two adjacent sheets to adhere together sufficiently that both sheets are sucked together onto the vacuum teed-head. Further, the coating of the paper may become sticky from heat and moisture, which may further strengthen the attractive forces causing the pieces of paper to adhere to each other. Similarly, either static forces or attractive forces may exist between exterior surfaces of two or more sheets of paper which prevent separation of the sheets of paper by the shuttle vacuum feed-head and/or the fluffer jets.
The static forces or the attractive forces between the sheets of paper may increase and/or may strengthen as the printing device is dead-cycling or is not processing images because of an environment within the paper feeder, for example, due to heat and/or moisture created by the device during dead-cycling. Traditionally, dead-cycling is a condition of the printing device in which one or more of the drive motors of the printing device are activated without producing output prints while an embedded control system performs print appearance adjustments. The environment within the paper feeder may contain moisture which may collected between one or more sheets of paper therein to increase the attractive forces between the sheets of paper. The environment within the paper feeder may also be a closed environment that includes heat generated from the paper feeder or the image forming device. This environment may encourage sticking of and attraction between sheets of paper within the paper feeder. The increased attractive forces prevent the sheets of paper in the stack from being readily separated after the imaging device has completed dead-cycling. Further, the pieces of paper may remain attached to each other because of the increased attractive forces therebetween when the vacuum feed-head picks up the top sheet of paper.
The shuttle vacuum feed-head may thus receive two or more sheets of paper from the stack instead of receiving only the top sheet of paper when the image forming device is activated after dead-cycling. As a result, the shuttle vacuum feed-head may receive more than one sheet of paper from the tray and may transfer more than one sheet of paper into the TAR. By transferring more than one piece of paper into the TAR, a multi-feed of paper occurs, which may cause a paper jam, a misprinted job, and can even damage inner mechanics of the imaging device. Additionally, the multi-feed of paper may result in the TAR not properly introducing additional sheets of paper into the image forming device. A multi-feed of paper is thus undesirable and/or costly in many potential ways, and should be avoided.
Traditionally, preventing multi-feeds of paper from entering the TAR or the image forming device after dead-cycling of the image forming device required that the stack of paper within the paper feeder be replaced with a new stack of paper. Static forces or attractive forces between sheets of paper within the new stack of paper may be weaker than the forces between the sheets of paper within the stack removed from the paper feeder. However, the closed environment may still contain moisture or heat from the image forming device or the paper feeder that encourages sticking and/or attraction between the sheets of the new stack of paper. Also, the constant use of new stacks of paper is impractically costly.
A need, therefore, exists for a method of controlling an environment within a media feeding device, particularly during dead-cycling, to minimize or prevent static and attractive force between adjacent sheets of stacked media for preventing or hindering separation of the individual sheets by the feeder. Further, a need exists for a method of controlling an environment within a media feeding device which reduces static forces or attractive forces between pieces of media in a stack during dead-cycling of an image forming apparatus. Still further, a need exists for a method of controlling an environment within a media feeding device which reduces a rate of multi-feeding of separate pieces (i.e., sheets) of the media into an image forming device. Moreover, a need exists for a method of controlling an environment within a media feeding device which fluffs, dries or separates pieces of media within a paper feeder to prevent damage to a take away roll or the image forming apparatus.